This document relates generally to providing electrical power from a fuel-powered generator and particularly, but not by way of limitation, to engine-generator set systems and methods providing load power fault protection.
Both businesses and households rely on electrical equipment powered from one-phase, two-phase, three-phase, or other suitable utility-provided alternating-current (AC) power sources. However, commercial power reliability may not suffice for certain applications, for example, for computer facilities, hospitals, banking systems, or industrial motor loads. Therefore, a backupxe2x80x94or even an independentxe2x80x94local power source may be desirable to provide a supplement to or substitute for a utility-provided AC power source.
One type of a local power source is a static system, which typically uses an inverter to generate the load""s AC power from a direct current (DC) battery bank. Providing power from such a static system for an extended period of time, however, may require a large and costly bank of batteries. Another type of local power source is a rotary system, which typically uses a fuel-powered engine to rotate the shaft of an AC generator to produce an AC load current for an extended period of time. The engine, generator, and associated control mechanisms are sometimes referred to collectively as a xe2x80x9cgenerator setxe2x80x9d or xe2x80x9cgenset.xe2x80x9d Both the generator and the engine of a genset may be damaged by an excessive electrical load. Moreover, certain protection schemes may protect the AC generator, but not the engine, from damage. Gensets using engines powered by natural gas or liquid propane (xe2x80x9cLPxe2x80x9d) gas are particularly susceptible to possible damage resulting from supplying an excessive electrical load. For these and other reasons, the present inventors have recognized a need for improved techniques of protecting genset components.
This document describes, among other things, systems and methods providing load fault power protection to an engine-generator set. In one example, the engine-generator set includes a load power fault protector circuit that detects when the power delivered to the load reaches a predetermined maximum power value, and substantially prevents the load power from exceeding the predetermined maximum value by decreasing the load voltage.
Among other things, this document describes an example of an overload protection apparatus for protecting an engine-generator set from damage. The overload protection apparatus includes a load power sensing circuit and a voltage regulator circuit. The load power sensing circuit includes an input configured for coupling to an engine-generator set load, and an output providing a load power signal measuring an indication of power delivered from the engine-generator set to the load. The voltage regulator circuit includes an output configured for coupling to a control input of a generator exciter circuit to control a voltage delivered from a generator to the load. The voltage regulator circuit also includes an input coupled to the load power sensing circuit output to receive the measured load power indication. In this example, the voltage regulator is configured to decrease a magnitude of the voltage delivered from the engine-generator set to the load when the measured load power indication reaches a predetermined maximum value to substantially prevent the load power delivered from the engine-generator set to the load from exceeding a maximum load power value.
Among other things, this document also describes an example of an engine generator set including an engine, a generator, a load power sensing circuit, and a voltage regulator circuit. In this example, the generator is mechanically coupled to and driven by the engine, and includes an output configured to be coupled to a load for providing electrical power signal to the load. The generator includes a generator exciter circuit controlling a load voltage of the electrical power signal provided to the load using a signal received at a generator exciter circuit control input. The load power sensing circuit includes an input configured for coupling to the load and an output providing a load power signal measuring an indication of power delivered from the generator to the load. The voltage regulator circuit includes an output configured for coupling to the generator exciter circuit control input to control the load voltage. The voltage regulator circuit also includes an input coupled to the load power sensing circuit output to receive the measured load power indication. In this example, the voltage regulator circuit is configured to decrease a magnitude of the load voltage when the measured load power indication reaches a predetermined maximum value to substantially prevent the load power delivered from the engine-generator set to the load from exceeding a maximum load power value.
Among other things, this document also describes a method of generating AC electrical power and delivering the electrical power to a load. In one example, this includes sensing a load power delivered by an engine-generator set to a load, determining whether the delivered load power has reached a maximum load power value, and, if the delivered load power has reached a maximum load power value, then decreasing a load voltage to clamp the load power about the maximum load power value. Other examples will be apparent on reading the following detailed description and viewing the drawings that form a part thereof.